Decelerating device



July 28, 1964 l H. w. scHoLlN 3,142,362

DECELERATING DEVICE Filed Aug. 14, 1962 ATT'YS B? w 9k,

United States Patent 3,142,362 DECELERATING DEVICE Harold W. Scholin, 7900 W. Belmont Ave., Chicago, lll. Filed Aug. 14, 1962, Ser. No. 216,898 10 Claims. (Cl. 18S- 96) The present invention relates in general to motion control, and has more particular reference to the deceleration of moving objects smoothly and without shock or jar. The motion control device of the invention may be used to decelerate and stop the moving parts of a machine without producing substantial shock forces between the moving part and the control device.

In accordance with the teachings of the present invention, the motion resistive force applied by the control device to decelerate a moving object is a constant force. This is achieved by the utilization of an hydraulic system in a device, the hydraulic fluid of which offers a constant resistance to a motion checking piston component of the device, which piston is set in motion upon engagement with a moving object to be stopped or buffered. The rate of deceleration of the buffered object may be predetermined by the clearances provided for regulating the flow of the hydraulic fluid in the system, taking into account the viscosity and other ow characteristics of the hydraulic fluid, the mass of the moving object to be decelerated, its initial velocity, and the mass of the piston. The rate of deceleration may be either linear or nonlinear, as desired.

lt is, therefore, a primary object of the invention to provide for the shockless deceleration of a moving object.

A further object of the invention is to provide a motion control device utilizing an hydraulic system to provide for the smooth linear or nonlinear deceleration to a moving body.

Still another object of the invention is to provide structural improvements in an hydraulic decelerating device.

^ The foregoing and numerous other important objects,

advantages, and inherent functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings:

FIG. l is a sectional View taken longitudinally of a device embodying the present invention; and

FIGS. 2 and 3 are sectional views taken, respectively, along the lines 2 2 and 3 3 in FIG. l.

Referring to the drawing, the motion control device comprises a hollow cylindrical barrel 1 constituting the hydraulic chamber of the motion control device, and another hollow cylindrical barrel constituting the reservoir chamber of the device, the barrels being mounted in coaxial end-to-end abutting relationship.

On the outer, open end of the barrel 1 is fixedly mounted a nose guide 3 having an axial channel 4 extending therethrough. The nose guide is held in fluid-tight contact with the outer edge of the barrel 1 by the use of aringshaped nose guide mounting plate 5 held in the barrel 1 against a snap retainer ring 6 secured in an annular groove in the inner wall of the barrel 1. The nose guide 3 is drawn tightly against the outer edge of the barrel 1 by four screws 7 having their heads seated in countersunk recesses of the inner face of the mounting plate 5 and their Shanks threaded in tapped holes in the inner face of the nose guide 3. By drawing these screws up tightly, the annular shoulder 8 of the nose guide 3 is drawn tightly against the outer edge of the barrel 1.

A hollow shank 9 of an hydraulic piston 10 is slidably mounted in the axial channel 4. The longitudinal passage through the shank 9 comprises coaxial passage segments 11, 12, the latter being of slightly larger diameter than the former. The piston structure includes a cylindrical recess 13 in the piston head 14 and an annular groove 15 in the side wall of the piston head 14 in which annular groove is mounted an oil seal O-ring 16. This O-ring prevents the escape of hydraulic fluid from the hydraulic chamber ahead of the piston in the barrel 1 behind the piston as it is moved in the barrel 1.

The outer end of the piston shank 9 is closed off with a threaded plug 17 having on the undersurface of the head of the plug 17 an oil seal ring 18. This plug 17 is the contact element against which impinges the moving object to be decelerated by the motion control device. A removable plug is preferred because it can be replaced in the event of damage caused by the impact of moving objects thereon without requiring replacement of the entire piston and its shank.

An orifice plate 19 is mounted in the barrel 1 against a snap retainer ring 20 seated in an annular groove in the barrel. The barrels 1 and 2 are held together by the employment of a reservoir cylinder mounting plate 21 which bears against a snap retainer ring 22 mounted in annular groove in the barrel 2. The orifice plate and the reservoir cylinder mounting plate are drawn together against their respective retainer rings by the use of screws 23 Whose heads bear against a face of the mounting plate 21 and whose threaded Shanks are threaded in tapped holes in the orifice plate 19.

The junction of the barrels 1 and 2 is sealed against oil leakage by the use of a retainer ring 24 bridging the junction between the barrels. The retainer ring 24 has an annular groove in which is mounted a pair of oil seal O-rings 25 which are pressed tightly against the inner walls of the barrels 1 and 2 adjacent the junction.

There is mounted in the orifice plate 19 a tapered, hollow plug 26 which extends into the hydraulic chamber of the barrel 1 in coaxial relationship with the passage segment 12 of the shank 9 of piston 10. This tapered, hollow plug has a forwardly tapered outer wall 27 and an axial passage 28 extending therethrough. The tapered plug is mounted on the orice plate 19 by means of a nut 29 threaded on the plug shank portion, which extends through a hole in the orifice plate 19.

The orifice plate 19 also has four small orifices 30 extending therethrough. These orifices are normally closed against hydraulic fiuid flow therethrough by means of a ring plate valve 31 seated against a face of the orifice plate 19 over the orifices 30. The ring plate valve 31 is urged against the face of the orifice 19 by a resilientmetal, ring valve spring 32 having its outer edge bearing against the plate 31 and its inner end bearing against a retainer ring 33 seated against a shoulder on the outer surface of the plug 26. The orifice plate 31 is slidable longitudinally on the cylindrical segment 35 of th plug 26.

The control device shown in FIG. l is in the position wherein the shank 9 of the piston 10 is fully extended and ready to receive the impact of a moving object which is to be decelerated. When the object hits the plug 17, the piston is driven to the right as viewed in FTG. 1 and the outer end of the tapered plug 26 enters the passage segment 12 of the shank 9. The passage segments 11, 12 and the piston chamber are lled with hydraulic liquid. In the first moments after impact, the hydraulic iiuid ows readily from the piston chamber through the axial passage 28 of the plug 26 because the outer end of the plug 26 has not yet entered the passage segment 12. However, as the end of the tapered plug 26 enters the passage segment 12 of the shank 9, the flow of hydraulic uid from the piston chamber of the barrel 1 into the axial passage 28 of the plug 26 is constricted because the fluid must pass between the tapered outer wall 27 of the plug 26 and the wall of the passage segment 12. The deeper the penetration of the plug 26 into the passage 12, the greater is the resistance to the flow of hydraulic iiuid from the piston chamber to the passage 28 because the annular space between the wall of the passage 12 and the tapered outer wall 27 becomes progressively smaller as a result of the progressively increasing diameter of the tapered wall 27. Therefore, as the piston 10 moves inwardly into the piston chamber, the resistive forces of the hydraulic uid against the movement of the piston becomes greater until the hydraulic resistance stops the piston. When the piston reaches the end of its stroke, the clearance between the wall of the passage segment 12 and the tapered plug 26 is almost zero. The piston 1i) will not bottom on the orifice plate 19, but rather the protruding edge of plug 17 will bottom on the outer end of nose guide 3 if the hydraulic resistance has not overcome the momentum of the moving mass prior to such bottoming.

The hydraulic fluid which Hows through the passage 28 of the plug 26 flows through a central passage 34 in the mounting plate 21 into a reservoir barrel 2. This uid pushes the iloating piston 36 away from the mounting plate 21 as the hydraulic iluid accumulates in the reservoir barrel 2. The floating piston 36 comprises a pair of piston heads 37 having annular grooves 38 in the side walls thereof in which are mounted oil seal O-rings 39. The piston heads 37 are interjoined by a shank 40 connected to the piston heads by screws 41.

The reservoir barrel 2 has a small weep hole 42 serving as a release passage for excess oil when the oating piston 36 is in proximity with the end of the reservoir barrel 2.

The reservoir barrel 2 has mounted at its open end a rear mounting plate 43 which bears against a snap ring 44 positioned in an annular groove in the inner wall of the reservoir barrel 2. The space between this plate and the oating piston, and also the space between the piston heads 37 of the floating piston, contain air. The oil in the reservoir barrel 2 is confined ahead of the oating piston 36.

The disc-shaped head 45 is mounted on the open end of the reservoir barrel 2 with its annular shoulder 46 resting on the outer end of the barrel 2. The head 45 is mounted on the end of the barrel 2 by means of screws 47 threaded into tapped holes in the rear mounting plate 43 to draw the rear mounting plate 43 and head 45 together against the snap ring 44.

The head 45 has an annular groove in Which is mounted a sealing `O-ring 48 which provides a substantially gastight seal between the head 45 and the reservoir barrel 2. The mounting plate 43 has a central passage 49 therein and the head 45 has a tapped passage 50 therein.

The purpose of the tapped passage 50 is to provide a connection for an air pressure line which is used to reset the hydraulic motion control device. The chamber 51 is vented to the atmosphere during the deceleration cycle of the device so that the iioating piston 36 can move toward the rear mounting plate 43 as oil flows into the reservoir barrel 2. This venting may be done by providing vent in the air pressure line, or by disconnecting the line from the tapped hole 50 during each deceleration cycle. The resetting cycle involves the driving of the oating piston 36 to the left, as viewed in FIG. 1, by high pressure air or other gas admitted through the passages 49, 50 into the chamber 51. This pressure drives the floating piston toward the reservoir cylinder mounting plate 21 and reverses the iiow of iiuid.

The hydraulic fluid in the reservoir barrel 2 can return to the piston chamber via the passage 28 in the plug 26. However, this return ow usually is impeded greatly by the narrow space between the tapered wall 27 and the wall of the passage segment 12 of the shank 9. An alternative passage for iiow of hydraulic fluid, therefore, is provided. This alternative passage is that of hydraulic fluid flow from the reservoir barrel 2 through the central passages 34 of plate 21 and then through the passages 30 of the orifice plate 19. The uid pressure is suflicient to overcome the spring load on the ring valve plate 31, and the fluid can iiow from the reservoir chamber into the piston chamber directly via the orifices 30. The ring plate valve 31 acts in the nature of a check valve between these chambers in allowing only unidirectional fluid ow via orifices 36 between chambers, i.e., from the reservoir chamber 2 to the hydraulic chamber 1. The check valve structure provides a faster, less turbulent return of the iiuid to the chamber 1 than would be the case of return flow only through plug 26, as well as less heat generation.

The outer wall 27 of the plug 26 and wall of the passage segment 12 of the piston shank coact to provide a clearance or orifice of changing size as the plug penetrates the passage segment. In the illustrated embodiment, this is achieved by the use of a cylindrical passage in the shank of the piston and a round outer wall of the plug which tapers in a direction toward the piston. These shapes may be reversed, i.e., a cylindrical outer wall on the plug and a tapered inner wall of the passage having its larger end nearest the plug. It is also Within the contemplation of the invention that both the outer wall of the plug and part or all of the coacting wall of the passage be tapered at the same or different degrees of taper. The rate of taper of the outer wall of the plug and/or the inner wall of the passage can be varied to give a linear or nonlinear rate of deceleration. The taper(s) may be linear or nonlinear, e.g., the outer wall 27 or the wall of passage segment 12 may be straight, as in a frusto-cone, concave or convex. Thus, the degree of taper may be constant or progressively increasing or decreasing.

It is advantageous to make the piston and its shank of lightweight material such as aluminum. When the shank is fully extended, the inertia of the mass of the piston and its shank is the initial resistive force to the moving mass striking against the end of the shank. When the mass of the piston and shank is small, there is only a small amount of shock at the initial impact of the moving mass against the end of the piston shank.

The device of the invention may be used in a wide variety of situations to decelerate a moving mass. For example, it can be used with indexing mechanisms to decelerate a turntable rotated in steps or stages by the indexing mechanism, e.g., the indexing mechanism of my U.S. Patent No. 2,826,099.

The motion control devices of the invention will provide a smooth deceleration to a moving mass which strikes against the piston shank without signicant shock at impact. The moving parts of my devices are few in number, and their amount of movement per cycle of operation is relatively small. This minimizes wear of the parts. The motion control devices operate on the principle of providing a progressively increasing hydraulic resistance to give the decelerating function.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacricing any of its attendant advantages, the form herein disclosed being a preferred embodiment f or the purpose of illustrating the invention.

The invention is hereby claimed as follows:

l. An hydraulic motion control device adapted to decelerate a moving mass comprising an hydraulic chamber, a movable piston in said hydraulic chamber, said piston being a solid piston with a shank with an axial passage therein, said passage also extending through said piston, said shank being slidably mounted in an end wall of said hydraulic chamber, the outer end of said shank being closed, hydraulic fluid sealing means slidably sealing the space between the periphery of said piston and the inner wall of said hydraulic chamber, a plug in said hydraulic chamber, said plug being coaxial with said axial passage and having an axial passage therethrough, said plug entering the axial passage through said piston and shank when said piston and shank are driven into said hydraulic chamber, the hydraulic fluid in said chamber being driven out of said chamber through the axial passage in said plug, and the plug and the axial passage in said piston and shank having a small clearance through which the hydraulic fluid must ow from said hydraulic chamber to the axial passage of said plug when said plug is in said axial passage.

2. An hydraulic motion control device as claimed in claim l wherein said clearance becomes smaller with increasing penetration of said plug into said axial passage.

3. An hydraulic motion control device adapted to decelerate a moving mass comprising an hydraulic chamber, an hydraulic fluid reservoir chamber, means communicating said chambers, a movable piston in said hydraulic chamber, said piston being a solid piston with a shank slidably mounted in an end wall of said hydraulic chamber, hydraulic uid sealing means slidably sealing the space between the periphery of said piston and the inner wall of said hydraulic chamber, and means on said piston coacting with said rst-mentioned means to provide a small clearance for hydraulic fluid flow from said hydraulic chamber through said irst-mentioned Vmeans into said reservoir chamber when said piston is driven toward said inst-mentioned means by a moving mass striking against said shank.

4. An hydraulic motion control device as claimed in claim 3 wherein said reservoir chamber has therein a floating piston which travels in said chamber as hydraulic fluid ows into said reservoir chamber from said hydraulic chamber.

5. An hydraulic motion control device as claimed in claim 3 wherein said means coacting with said first-mentioned means provides a clearance which becomes progressively smaller as the piston moves in said hydraulic chamber under said force against said shank.

`6. An hydraulic motion control device adapted to decelerate a moving mass comprising an hydraulic chamber, a movable piston in said hydraulic chamber, said piston being a solid piston with a shank with an axial passage therein, said passage also extending through said piston, said shank being slidably mounted in a wall at one end of said hydraulic chamber, the outer end of said shank being closed, a ring seal slidably sealing the space between the periphery of said piston and the inner wall of said hydraulic chamber, an hydraulic uild reservoir chamber positioned adjacent the opposite end of said hydraulic chamber, a plug in said hydraulic chamber, said plug being coaxial with said axial passage and having an axial passage therethrough communicating said reservoir chamber and said hydraulic chamber, said plug entering the axial passage through said piston and shank when said piston and shank are driven into said hydraulic chamber, the hydraulic uid in said chamber being driven out of said chamber through the axial passage in said plug, and the plug and the axial passage in said piston and shank having a small clearance through which the hydraulic 6, fluid must flow from said hydraulic chamber Ato the axial passage of said plug when said plug is in said axial passage, and a tloating piston in said reservoir chamber, which floating piston travels in said reservoir chamber as hydraulic fluid flows into said reservoir chamber from said hydraulic chamber.

7. An hydraulic motion control device as claimed in claim 6 wherein said plug is mounted in and extends through a wall across said opposite end of said hydraulic chamber, and check valve means on said wall directly communicating said chambers and permitting ow of hydraulic iluid also through said check valve means only from said reservoir chamber to said hydraulic chamber.

8. A hydraulic motion control device comprising a hollow cylindrical barrel divided by a cross wall in said barrel into a hydraulic uid chamber at one end of said barrel and a hydraulic fluid reservoir at the other end of said barrel, a nose guide with an axial passage therethrough iixedly held on said one end of said barrel, a movable piston in said hydraulic chamber, said piston being a solid piston with a shank having an axial passage therein, said passage also extending through said piston and opening into said hydraulic chamber, said shank being slidably mounted in said axial passage of said nose guide, the outer end of said shank being closed by a removable strike plug, a plug mounted in said cross wall and extending toward said piston, said plug being coaxial with said axial passage of said shank and having an axial passage therethrough communicating said hydraulic uid reservoir with said hydraulic chamber, said plug entering said axial passage of said shank and piston when said piston and shank are driven toward said cross wall, the hydraulic uid in said chamber being driven out of said chamber through said axial passage in said plug into said reservoir, a floating piston slidably and axially movable in said hydraulic fluid reservoir, said iloating piston including an axial shank and a solid piston head at each end of said shank, sealing means slidably sealing the spaces between the peripheries of each of said piston heads and the inner wall of said hydraulic fluid reservoir, the wall of said hydraulic uid reservoir having a vent pas sage therethrough communicating the interior and exterior of said reservoir at a point between said piston heads of said floating piston, said iloating piston being adapted to move away from said cross wall as hydraulic fluid is forced from said hydraulic chamber into said reservoir by hydraulic pressure exerted against the piston head closest to said cross wall and also being adapted to move toward said cross wall by the exertion of uid pressure in said reservoir at said other end of said barrel against said piston head of said floating piston farthest from said cross wall, the plug and the axial passage in said piston and shank having a small clearance through which the hydraulic iluid must flow from said hydraulic chamber to the axial passage of said plug when said plug is in said axial passage, and passage means at said other end of said barrel for introducing a fluid under pressure to drive said floating piston toward said cross wall and thereby force hydraulic tluid from said reservoir into said hydraulic chamber and thereby also drive said piston in said hydraulic chamber away from said cross wall.

9. A hydraulic motion control device as claimed in claim 8 wherein said hollow, cylindrical barrel comprises two axially aligned, abutting, hollow, cylindrical, barrel members with the joint therebetween positioned substantially at the line of demarcation between said hydraulic chamber and said hydraulic reservoir, a retainer ring bridging the abutting ends of said barrel members, said retainer ring having an annular groove in the outer peripheral wall thereof, ring seal means sealing said annular groove against hydraulic fluid loss through the junction of said abutting ends, a mounting plate having a hydraulic fluid passage therethrough mounted in said hydraulic fluid reservoir adjacent said retainer ring, said cross wall being mounted adjacent the opposite side of said 7 mounting ring in said barrel member defining said hydraulic chamber, and a plurality of screws extending between said retainer ring and said cross wall and rigidly holding said cross wall in said barrel member.

10. A hydraulic motion control device as claimed in 5 claim 9 wherein each of said barrel members has adjacent the respective sides of said retainer ring an annular groove, a snap retainer ring seated in each annular groove on opposite sides of said rst-mentioned retainer ring, and said mounting plate and said cross wall being drawn by said screws tightly against the opposite sides of said snap retainer rings.

References Cited in the le of this patent UNITED STATES PATENTS Krone Oct. 13,

Philpott et al. Mar. 3,

Sinclair May 2,

Swales et al. Feb. 6,

Blackburn Aug. 20,

FOREIGN PATENTS France Aug. 22, 

1. AN HYDRAULIC MOTION CONTROL DEVICE ADAPTED TO DECELERATE A MOVING MASS COMPRISING AN HYDRAULIC CHAMBER, A MOVABLE PISTON IN SAID HYDRAULIC CHAMBER, SAID PISTON BEING A SOLID PISTON WITH A SHANK WITH AN AXIAL PASSAGE THEREIN, SAID PASSAGE ALSO EXTENDING THROUGH SAID PISTON, SAID SHANK BEING SLIDABLY MOUNTED IN AN END WALL OF SAID HYDRAULIC CHAMBER, THE OUTER END OF SAID SHANK BEING CLOSED, HYDRAULIC FLUID SEALING MEANS SLIDABLY SEALING THE SPACE BETWEEN THE PERIPHERY OF SAID PISTON AND THE INNER WALL OF SAID HYDRAULIC CHAMBER, A PLUG IN SAID HYDRAULIC CHAMBER, SAID PLUG BEING COAXIAL WITH SAID AXIAL PASSAGE AND HAVING AN AXIAL PASSAGE THERETHROUGH, SAID PLUG ENTERING THE AXIAL PASSAGE THROUGH SAID PISTON AND SHANK WHEN SAID PISTON AND SHANK ARE DRIVEN INTO SAID HYDRAULIC CHAMBER, THE HYDRAULIC FLUID IN SAID CHAMBER BEING DRIVEN OUT OF SAID CHAMBER THROUGH THE AXIAL PASSAGE IN SAGE IN SAID PLUG, AND THE PLUG AND THE AXIAL PASSAGE IN SAID PISTON AND SHANK HAVING A SMALL CLEARANCE THROUGH WHICH THE HYDRAULIC FLUID MUST FLOW FROM SAID HYDRAULIC CHAMBER TO THE AXIAL PASSAGE OF SAID PLUG WHEN SAID PLUG IS IN SAID AXIAL PASSAGE. 